A multiport repeater, hereinafter "Hub", is an integral part of Digital Equipment Corporations Ethernet wiring system for local area networks (LANs). A multiport repeater is a device which performs signal conditioning on a received signal, wherein, the signal is amplified and timing margins are restored. The product announcement for this wiring system is incorporated by reference. This system is designed to deliver ten mega-bits per second Ethernet peformance and full DECnet (DECnet refers to Digital Equipment Corporation's networking capability) functionality to the desk and work area for connection of PCs, workstations, network servers, and low-end computing devices.
Standard Ethernet cabling (particularly transceiver cable) and transceivers are expensive and difficult to use for attaching equipment in the work area. Whereas, the system of the invention meets office and work area requirements by offering low-cost, flexible, and easy to install cables, thus improving flexibility and reducing the cost of standard Ethernet products for the user environment. Additionally, the system of the invention provides for a "radial" wiring scheme. The hub, configured radially, connects eight thin coaxial cable segments (RG58), each up to 185 meters in length. Up to twenty-nine (29) workstations can be serially "daisy-chained" on each segment. Since the thin cable of the invention is limited to a range of 185 meters, the radial topology provides for an extensive LAN which is not possible with a single run of thin cable. The hub can be implemented by itself in a stand alone network hub, or, connected to a standard Ethernet "backbone".
Both the improved Ethernet system of the invention and the standard Ethernet system have distinct advantages in different environments. The two wiring schemes are compatible and can be interconnected for resource sharing across an entire network. The combination of standard Ethernet and the improved Ethernet system of the invention offers excellent natural growth from small resource sharing networks to large global networks.
Standard Ethernet products use an H4000 transceiver (or the new H4005 transceiver) which taps directly into an Ethernet coaxial cable. The H4000 (15-pin D connector) is coupled to the hub (15-pin D connector) by a transceiver cable.
The cabling system of the invention employs a technique called daisy-chaining, wherein a different tap, called a T-Connector, is used to join two segments of RG58 C/U cable. The bottom of the "T" is inserted directly into a PC/Workstation. Devices connected to the cable either have an integral Ethernet controller and transceiver functionality, or have a "ThinWire Ethernet Station Adapter" (DESTA) to adapt the device for use with thin cabling.
The Ethenet cabling system of the invention will best serve users in the floor area of a facility, wherein standard Ethernet cabling techniques are employed between floors and buildings at a customer site. For example, the three major configurations for the cabling system of the invention include work area networks, stand-alone LANs and global LANs.
Work area networks are defined as small standalone local area networks, wherein multiple PC/Workstation users in a work area share resources, such as printers and storage devices.
Standalone LANs are defined as small- to medium-sized standalone LANs in a small business, or in the department of a larger organization, where PC/Workstation users have the need for local resource sharing, including more powerful computing resources. The hub can be used in a radial topology to interconnect PCs, servers and computers in a work area or throughout the floor of a building. Each of the eight coaxial cable segments that connect to the hub can accommodate up to twenty-nine (29) stations. A segment can be up to 185 meters long. Therefore, a single hub has the potential of interconnecting up to 232 stations.
Global LANs are defined as medium-to-large-sized LANs which serve a large corporation or medium-sized business whose users need local resource sharing, as well as substantial computing access. In this case, the improved system of the invention serves as a subnetwork which is connected to the standard Ethernet "backbone" for access to network computing resources on the large Ethernet and at remote locations.
In this case, many smaller LANs are connected to the standard Ethernet backbone with the H4000 or H4005-B transceiver. (A description of the new H4005 transceiver is incorporated by reference).
The cabling system of the invention employs the hub and associated thin cabling in a radial fashion, originating in satellite closets to serve the facility floor.
When the hub is placed in satellite distribution closets and uninterrupted (i.e., not daisy-chained) the system employs runs of RG58 C/U cable from the hub directly to a wall plate mounted in an office. This maintains the integrity of the cable system and provides for proper management of the network cabling system.
Users can connect a length of RG58 C/U cable from a station to the wall plate. Within the office, PCs or servers could be daisy-chained. By installing eight hubs in a satellite closet, up to 64 offices could be served, and a much large number of devices can be connected to the network via daisy-chaining in the offices.
In the improved Ethernet cabling system of the invention, standard Ethernet is specified to interconnect floors within a building, and the buildings of a site. Standard Ethernet coaxial cable is designed with lower signal attenuation than the thin cable of the invention, allowing longer cableruns. It also has a somewhat higher resistance to EMI/RFI and has high quality connectors (this accounts for it being more expensive).
These features are critical for the cabling used between floors and closets, since it is generally less accessible than floor wiring. Standard Ethernet provides the cabling integrity required for interconnection of thin cable subnetworks and large numbers of devices. The thin cable system of the invention is better suited for attachment of devices on the floor itself.
In order to serve up to 64 offices from a wiring closet, it is necessary to configure multiple hubs in a closet.
A Digital Equipment local network interconnect (DELNI) may be used as a concentrator for up to eight hubs in either a standalone or global configuration. In both cases, a network with the potential to connect over 1,000 daisy-chained devices can be configured. (8 hubs.times.8 segments/hub.times.29 stations/segment; 1,024 is the Ethernet limit.)
When part of a global configuration, the DELNI/hub "sub-network" is connected to the standard Ethernet backbone with an H4005-B transceiver. In local configurations, the DELNI/hub configuration is simply NOT connected to a standard Ethernet segment.
The hub serves as a repeater between all stations attached to it. When it is connected to a standard Ethernet, it functions as a repeater between all stations attached to it and all devices connected to the standard Ethernet. The hub must be counted as a full repeater when configuring an Ethernet LAN. The hub has repeater logic between all ports, including partitioning logic which fault isolates each office when an office has its own dedicated port.
Since each hub counts as a repeater, only one other repeater can be configured in the path between the hub and any station on the rest of the Ethernet.
For configuration simplicity, it is recommended that bridges (DEBET) rather than repeaters (DEREP) be used between standard Ethernet segments where hubs are attached.